10 intervals, 30 running, 60 walking, done with a bit of care because I'm back at work.

Last week, I was having to be very cautious, and found that 9 intervals was kind of my safe limit, and now, a week later, 10 intervals, all a tiny bit more than 30 seconds, seems safe.

This violates all of the rules I've learned about exercise - I'm not trying for steady heart rate in the training zone, 10 intervals is 14 minutes (I don't count the final 60 second walking-rest), rather than the 20 that "everyone knows" that you need to improve your heart.

But my legs are a bit achy from the exercise, meaning I'm strengthening my leg muscles. My sciatic fires off an occasional twinge, suggesting I'm still shaking out how my legs work. And my heart is definitely being challenged, meaning that it should be getting stronger.

I hate how slow this is, but then, I'm 44 years old, 265 lbs or so, and was idled for a long time with an injury. Being patient is necessary.